Figured I would start a blacklist dump thread, some of you might also be interested in perimeter security, and I think blacklisting is a useful strategy.
Here is a blacklist I personally painstakingly compiled for use with Squid proxy.
Porn - Malware - Drive By Exploit sites - Ads -
Now heres a really special blacklist. (Ill be posting it soon, ive got to format it for general use)
US mil/government and other uber seecret unwanted hosts.
many of these hosts were taken from multiple publicly available lists, and dramatically expanded by probing nearby ranges, many uber seecret goobermant hosts you will not find anywhere else are contained in this blacklist.